Fluid-cooled active part, electric machine, and drive system

ABSTRACT

The invention relates to a fluid-cooled active part ( 1 ) for an electric machine ( 38 ), wherein the active part (1) is substantially cylindrical or hollow cylindrical, having axially extending grooves ( 2 ), at least one electrical conductor ( 3 ), which is arranged in the associated groove ( 2 ) at least in some sections and which is composed of a plurality of partial conductors ( 4 ), one or more main insulators ( 5 ), each arranged between the associated conductor ( 3 ) and the associated groove ( 2 ), and partial-conductor insulators ( 6 ), each surrounding the associated partial conductor ( 4 ). The invention further relates to an electric machine ( 38 ), having such a fluid-cooled active part ( 1 ) designed as a stator ( 39 ) and/or such a fluid-cooled active part ( 1 ) designed as a rotatably mounted rotor ( 40 ), wherein the electric machine ( 38 ) can be operated with a voltage in the range of at least a few kilovolts, preferably a few tens of kilovolts. Finally, the invention relates to a drive System ( 41 ), having such an electric machine ( 38 ) and a fluid energy machine ( 42 ) for the fluid, wherein the fluid energy machine ( 42 ) is designed as a compressor, in particular for process gas, or as a pump, in particular for a process liquid. In order to provide, among other things, a high-performance fluid-cooled active part that is compact and, in particular, resistant in the environment of the fluid or of a process fluid, it is proposed, among other things, that the active part ( 1 ) has one or more cooling Channels ( 7 ) for conducting the fluid, in particular a process fluid, wherein each cooling Channel ( 7 ) is arranged between the associated main insulator ( 5 ) and the respective partial-conductor insulators ( 6 ).

The invention relates to a fluid-cooled active part for an electric machine, wherein the active part is essentially cylindrical or hollow cylindrical, having

-   -   axially extending grooves,     -   at least one electrical conductor which in each case is arranged         at least in certain sections in the respective groove and which         is composed of a plurality of sub-conductors,     -   a respective main insulator, which is arranged between the         respective conductor and the respective groove, and     -   a respective sub-conductor insulator which surrounds the         respective sub-conductor.

Furthermore, the invention relates to an electric machine having

-   -   a fluid-cooled active part of this kind designed as a stator         and/or     -   a fluid-cooled active part of this kind designed as a rotatably         mounted rotor,

wherein the electric machine can be operated with an electrical voltage in the range of at least a few kilovolts, preferably a few tens of kilovolts.

Finally, the invention relates to a drive system having an electric machine of this kind and a fluid energy machine for the fluid, wherein the fluid energy machine is designed for example as a compressor, in particular for a process gas, or as a pump, in particular for a process liquid.

An active part of this kind and an electric machine of this kind are used for example when conveying oil and gas. A trend in the development of machines for the oil and gas sector is the integration of the drive motor in the housing of the machine with the primary goal of being able to dispense with the seal on rotating parts. These are referred to as hermetically sealed systems. However, this also creates the possibility of motor components coming into contact with the process gas. In many applications it is even desirable to cool the motor directly by the process gas in the primary cooling circuit.

Process gases can contain chemically aggressive media, which then lead to accelerated aging of materials. Often process gas must be taken to mean a slightly refined gas as it is extracted from a well. Furthermore, the gas pressure in the cooling circuit roughly corresponds to static pressure of the process gas and—depending on the process control and special situations—is subject to strong fluctuations. Pressures up to 200 bar can occur. A third problem is the frequently high water content in the gas, which brings an increased electrical conductivity with it. In many cases, the inflowing cooling gas is saturated with water. Other liquids can also be part of the cooling medium.

Passive components should usually be protected from aging by metallic coatings or the use of alternative materials. In the case of the active parts of the motor, other material parameters, such as the magnetic permeability or electrical conductivity are of such importance that the use of resistant metallic materials or coating with such materials would lead to significantly poorer performance.

Traditionally film and fabric layers with additional components are applied in order to insulate the windings of an electric machine, and these are then saturated with a synthetic resin. Many of the materials used are not resistant to the above-described gases or gas-liquid compositions. A conventional insulating system can be destroyed even by high static pressure.

One variant of motors for hermetically sealed compressors is designed as a canned motor. The can is used for sealing between stator and rotor cooling space. While the rotor is cooled by the process gas, oil flows through the stator. This variant has been found to be technologically complex, and the possible main dimensions are determined by the strength limits of the can. With asynchronous machines, the air gap sometimes has to be extended, which in turn leads to a lower power factor and, consequently, to a larger power converter, owing to the working principle of this machine type.

In a second variant of motors, process gas flows through or over the rotor and the stator. The known motors, which are cooled with gas under high static pressure, are insulated with resin-saturated films and strips, with the materials being as insensitive as possible to the process gas. The technology for producing an insulating system of this kind is based on the traditional technology of winding insulation and saturation in the field of large electric machines and only requires some adjustments due to the materials used. The synthetic resin, which is conventionally introduced in a vacuum impregnation method, performs tasks of insulating, bonding and stiffening of the winding.

One problem is the sensitivity to moisture absorption, in particular after delamination of the main insulator. Delamination can be caused by pressure cycling in the process. The formation of a single conductive channel between a phase winding to ground potential or to a different phase element already leads to complete failure of the machine.

From US 2010/0264761 A1 a machine having a gas compressor and a rotating electric machine for driving the gas compressor is known, wherein the electric machine has a first and a second electrical insulator with polyetheretherketone (PEEK).

From EP 1 863 152 A2 a stator assembly for an electric machine is known, which is used to transport the liquid, for example oil or gas, through pipelines.

From EP 1 967 286 B1 an encapsulated stator assembly is known which can be used for example for compressors in the oil and gas industry.

From EP 2 267 869 B1 an electric machine with a seal assembly is known for use in corrosive environments.

From DE 10 2009 003 424 AI an electric drive with a pressure housing is known for gas pipeline and storage compression applications.

An object of the invention is to overcome the drawbacks of the prior art and to provide a fluid-cooled active part which is powerful, compact and in particular resistant in the environment of the fluid or a process fluid. A further object of the invention is to provide an electric machine or a drive system with an active part of this kind.

A solution to the object is achieved for an active part of the type mentioned in the introduction by way of a respective cooling channel for guiding the fluid, in particular a process fluid, wherein the respective cooling channel is arranged between the respective main insulator and the respective sub-conductor insulator.

A solution to the further object is achieved for an electric machine or a drive system of the type mentioned in the introduction in that the electric machine or the drive system has a fluid-cooled active part of this kind designed as a stator and/or a fluid-cooled active part of this kind designed as a rotatably mounted rotor, or an electric machine of this kind.

The proposed fluid-cooled active part is in particular cylindrical in an embodiment as a rotor and hollow cylindrical in an embodiment as a stator for an electric machine. Accordingly, an axial direction along a machine axis and a radial direction are outwardly predefined by the machine axis. A corresponding cylinder coordinate system is completed by a circumferential direction perpendicular to the radial direction and around the machine-axis.

The active part has axially extending grooves which in the embodiment as a rotor or stator for an inner rotor are arranged at the radial outer side or inner side of the active part, in particular as open grooves. In particular, the grooves can be incorporated into a laminated core or the like of the active part. Arranged in the respective groove is at least one electrical conductor which in each case is led out via a winding head region at the respective axial end face of the active part of the one groove and is inserted in the next groove.

The respective conductor is divided into a plurality of sub-conductors, wherein a respective sub-conductor insulator is provided for the individual sub-conductors and a main insulator is provided for insulating the respective conductor against the respective groove or against the laminated core. What is known as a high-performance plastic, such as, for example polyetheretherketone (PEEK), is preferably used for the respective main insulator and/or the respective sub-conductor insulator.

Polyetheretherketone has a number of advantages, such as for example, a particular chemical and temperature resistance. This for example makes itself noticeable in that the material can be permanently used up to a temperature of 250° C. and, furthermore, has a high resistance to chemically aggressive substances, in particular aqueous acids. PEEK is therefore particularly suitable for applications involving sour gas, such as, for example untreated natural gas, or with acidic liquids, such as untreated crude oil. In addition to its resistance to hydrolysis and its good mechanical creep resistance, its electrical impact strength of 25 kV/mm makes the material particularly suitable for use in the proposed electrical active part or the proposed electric machine, which can be operated with an electrical voltage of a few kilovolts or a few tens of kilovolts.

The proposed active part is characterized inter alia by the respective cooling channel which in each case is arranged between the respective main insulator and the respective sub-conductor insulator and by means of which the fluid, in particular a process fluid, is guided within the active part. As already indicated, the fluid can be in the form of a liquid or gas and in particular a process liquid, such as for example crude oil, or a process gas, such as for example natural gas. Since the fluid is guided in the respective cooling channel between the respective main insulator and the sub-conductor insulator, particularly direct cooling of the respective conductor is achieved. The heat losses resulting during the operation of the active part can therefore be transported away virtually directly at the site of origin, with thermal insulating paths that hinder heat transport being kept as low as possible.

Due to suitable insulating materials, such as for example, the high-performance plastic discussed above, an electrical isolation of the respective sub-conductors and the respective conductor can be ensured even under adverse environmental conditions, such as for example, in the flowing around of the process fluid. Due to said very direct cooling of the respective conductor, a high power density of the machine can be achieved despite the additional space required for the cooling channels in the respective groove. The present invention therefore allows, in particular due to the proposed guidance of the respective cooling channel, a powerful and compact active part to be provided.

Preferably, the proposed active part can also be operated with an electrical voltage in the range of at least a few kilovolts, preferably a few tens of kilovolts. In particular, the proposed active part or the proposed electric machine or the proposed drive system can be operated with an electric power of a few megawatts to a few tens of megawatts. The electric machine is preferably designed as an electric motor, with, in principle, an embodiment as a generator also being conceivable.

The fluid energy machine can be designed in particular as a thermal or hydraulic flow or piston engine. For example, turbo-compressors for gases or turbo or centrifugal pumps for liquids, can be considered as thermal or hydraulic flow machines, and for example, piston compressors for gases or piston pumps for liquids can be used as thermal or hydraulic piston machines. The process fluid of the fluid energy engine is preferably used as the fluid for cooling the proposed active part or the proposed electric machine. The process fluid can be gaseous, in particular be in the form of natural gas, or be liquid, in particular in the form of crude oil, with the fluid energy machine being designed accordingly, as described above.

In an advantageous embodiment of the invention, the respective cooling channel has an inlet channel, an outlet channel and a respective connecting channel for fluidically connecting the inlet channel to the outlet channel, wherein the respective groove has a groove base and two groove walls, wherein the respective inlet channel or outlet channel is arranged between the respective conductor on the one hand and the groove base or the groove opening opposite the groove base in the radial direction on the other hand, wherein the respective connecting channel is arranged at least predominantly between the respective conductor on the one hand and one of the two groove walls on the other hand.

This kind of design of the respective cooling channel ensures that the fluid can flow along the side surfaces of the respective conductor, viewed in the circumferential direction, and causes a good removal of the heat losses resulting in the respective conductor during operation. For this purpose, in each case an inlet channel is provided between the respective conductor and the groove base and an outlet channel is provided between the respective conductor and the groove opening, wherein the connecting channel produces a connection between the inlet channel and the outlet channel. The respective inlet channel and the respective outlet channel in the axial direction are preferably largely formed continuously along the respective groove.

The respective connecting channel ensures, in particular, that the fluid predominantly flows in the radial direction from the respective inlet channel to the respective outlet channel. A flow component can also be provided along the axial direction, especially if an axial offset is present between the respective input and the respective outlet. An offset of this kind occurs, for example, due to the fact that the respective inlet is arranged at one of the end faces of the respective groove and the respective outlet at the opposing end face or, for example, is arranged in the region of the axial center of the respective groove.

A type of spacer or other support structure can, for example, be provided for the formation of the respective cooling channel.

In a further advantageous embodiment of the invention, the respective main insulator has two essentially C-shaped insulating half-shells, which together essentially surround the respective conductors in a plane perpendicular to the axial direction, with the two respective insulating half-shells being arranged essentially symmetrically to the groove center in the circumferential direction of the respective groove, wherein the two respective insulating half-shells are sealed in the radial direction by means of a respective sealing element, comprising in particular a fluororubber.

In a cross-section perpendicular to the axial direction through the active part, the respective conductor is therefore surrounded by the two insulating half-shells. The respective insulating half-shell has an essentially C-shaped cross-section in this plane, with the two insulating half-shells facing each other and being arranged essentially symmetrically to the groove center. This produces two supporting or contact lines radially inwardly and radially outwardly for the two insulating half-shells, with a respective sealing element for sealing the respective main insulator in the radial direction being provided on these lines extending in the axial direction.

To simplify the sealing of the two insulating half-shells in the radial direction and to make it more reliable, the respective insulating half-shell can in each case have a kind of hook in the region of the supporting or contact lines, which hook points in the radial direction toward the respective conductor. An enlarged supporting or contact surface respectively is formed as a result.

As a sealing material for the respective sealing element in particular a fluororubber is used here, which is characterized by its chemical resistance, even in adverse environmental conditions, and good electrical insulator properties. The fluororubber (FPM) can be present, for example in the form of a perfluoro rubber (FFPM).

In an alternative, advantageous embodiment of the invention, the respective main insulator at least largely covers the groove base and the two groove walls of the respective groove, wherein a plurality of channel half-shells is arranged one behind the other in the axial direction, with the respective channel half-shell having an essentially U-shaped cross-section in a plane perpendicular to the axial direction and largely surrounding the respective conductor in this plane.

The respective main insulator therefore lines the respective groove and ensures a reliable electrical isolation between the respective conductor and, for example, the laminated core of the active part. The respective conductor is positioned in particular by the channel half-shells within the respective groove, with the respective channel half-shells having an essentially U-shaped cross-section in a cross-section perpendicular to the axial direction. The respective channel half-shell is arranged in such a way that it largely surrounds the respective conductor, viewed in this cross-section, so the respective U of the respective channel half-shell points in one or the other circumferential direction.

For example, some of the channel half-shells are arranged mirror-inverted to the other channel half-shells with respect to the groove center in the circumferential direction of the respective groove. In accordance with this example, the channel half-shells are arranged in such a way that some point in the one circumferential direction and some in the other, opposite circumferential direction. In particular, the channel half-shells ensure guidance of the fluid in addition to positioning and the electrical insulation of the respective conductor.

In a further advantageous embodiment of the invention, the respective channel half-shell, viewed in a plane perpendicular to the axial direction, have at least one radial web extending along the respective conductor in the radial direction, and two pairs of circumferential webs pointing in the circumferential direction, which are connected by means of the radial web, wherein the one pair of circumferential webs is designed for forming the respective inlet channel and the other pair of circumferential webs is designed for forming the respective outlet channel, wherein, in at least a first channel half-shell, in each case at least one of the two central circumferential webs is designed for forming at least some of the respective connecting channel.

The cross-section of the respective channel half-shell perpendicular to the axial direction can be well illustrated, for example, using the letter “E”, which consists of one vertical and three horizontal lines. Here, the radial web or a circumferential web of the respective channel half-shell corresponds to the vertical line or a horizontal line of the “E”. Unlike the letter “E”, however, the respective channel half-shell has two pairs of circumferential webs and therefore four circumferential webs instead of only three horizontal lines in the letter “E”.

The respective channel half-shell is designed in such a way that the, for example, radially inner and radially outer pair of circumferential webs together with the radial web largely surrounds the respective inlet channel or outlet channel. Preferably, the respective conductor is arranged between the two middle circumferential webs. The respective radial web extends in the radial direction along the respective conductor and is advantageously arranged between the respective conductor on the one hand and one of the two corresponding groove walls.

The channel half-shells comprise in this case at least a first channel half-shell, by means of which at least some of the respective connecting channel is formed. In particular, the respective first channel half-shell ensures a sufficient cavity between the respective conductor on the one hand and the corresponding groove wall on the other hand for the respective connecting channel. For example, the respective cavity is arranged opposite the respective radial web in the circumferential direction in relation to the respective groove center. In particular, the respective first channel half-shell can provide a connection of the respective inlet channel and/or the respective outlet channel to the respective connecting channel.

In a further advantageous embodiment of the invention, a respective through-opening remains between at least one of the two central circumferential webs of the respective first channel half-shell on the one hand and the respective main insulator on the other hand and/or at least one of the two central circumferential webs of the respective first channel half-shell has a respective through-opening.

The respective through-opening therefore constitutes a part of the respective connecting channel, by means of which the fluid can flow from the respective inlet channel into the region to the side of the respective conductor and/or the fluid can flow from the region to the side of the respective conductor into the respective outlet channel. The region to the side of the respective conductor is arranged to adjoin the respective conductor in the circumferential direction.

The respective through-opening is arranged at one or both of the two central circumferential webs of the respective first channel half-shell or remains between one of these circumferential webs on the one hand and the respective main insulator on the other hand.

In a further advantageous embodiment of the invention, with at least one second channel half-shell, in each case the circumferential webs of at least one of the two pairs of circumferential webs are connected by means of a respective end web in such a way that the respective second channel half-shell, viewed in a plane perpendicular to the axial direction, has a rectangular cross-section for guiding the respective cooling channel.

The respective end web is preferably arranged opposite the respective radial web in the circumferential direction in relation to the respective groove center. The respective end web on the one hand allows good guidance of the flowing fluid and on the other hand, increased mechanical stability since in particular the respective conductor is additionally supported in the radial direction.

In a further advantageous embodiment of the invention, at least two electrical conductors are arranged in the respective groove one above the other in the radial direction, with a respective intermediate element for sealing and/or tolerance compensation being provided, and this is arranged in the radial direction between one of the half-shells of the upper electrical conductor on the one hand and one of the half-shells of the lower electrical conductor on the other hand.

If two electrical conductors designed as a bar winding are arranged in the respective groove, that electrical conductor which is arranged closer to the groove opening or on the groove base is often characterized as an upper or lower bar. However, arrangement of more than two electrical conductors in the respective groove is also conceivable.

Channel half-shells are associated with each of the conductors in the groove, and these largely surround the respective conductor, viewed in a cross-section perpendicular to the axial direction, in pairs. In this case, a respective intermediate element is provided between the half-shells of adjacent conductors, and this is used for sealing and/or tolerance compensation. A seal is advantageous to avoid undesirable flow losses between the inlet channel and the outlet channel of adjacent conductors. Tolerance compensation has the advantage that manufacturing tolerances can be roughly adhered to and this saves costs. Furthermore, the complete arrangement located in the respective groove in the radial direction can be fixed, for example by means of a groove closure at the respective groove opening, and therefore in particular wobbling of this arrangement can be reliably prevented.

For the respective intermediate element, in particular a fluororubber can be used which, as has already been explained above, is characterized by its chemical resistance, even under adverse environmental conditions, and good electrical insulating properties. The fluororubber (FPM) can also be present, for example, in the form of a perfluoro rubber (FFPM).

In an alternative advantageous embodiment of the invention, the respective main insulator at least largely covers the groove base and the two groove walls of the respective groove, wherein at least two electrical conductors are arranged in the respective groove one above the other in the radial direction, wherein a respective conductor shell is provided which surrounds the respective conductor in a plane perpendicular to the axial direction, with both the respective groove, at least in the region of the lower electrical conductor and the respective conductor shell of the lower conductor, tapering in the direction of the groove base in such a way that the respective conductor shell of the lower conductor is positively fixed in the direction of the groove base and a first, axially extending cavity, in particular for a first inlet channel, remains between the groove base and the respective conductor shell of the lower conductor.

The respective main insulator therefore lines the respective groove and ensures a reliable electrical isolation between the respective electrical conductor and, for example, the laminated core of the active part. The respective electrical conductor is positioned in particular by the respective conductor shell within the respective groove, wherein the respective conductor shell largely surrounds the respective conductors, viewed in the cross-section perpendicular to the axial direction.

If, for example, two electrical conductors are arranged one above the other in the respective groove, they are often referred to as an upper bar or lower bar if they are designed as a bar winding. Here, the upper bar or lower bar is that electrical conductor which is arranged closer to the groove opening or the groove base.

Particularly good fixing of the lower conductor in the respective groove is achieved in particular by the following arrangement. In principle, the respective groove can have a constant groove width in the circumferential direction from radially inside to radially outside. However, a taper of the respective groove in the direction of the groove base is provided, at least in the region of the lower conductor, with the respective conductor shell of the lower conductor also having a corresponding taper in the direction of the groove base. The corresponding tapers are designed in such a way that the respective conductor shell of the lower conductor is positively fixed in the respective groove in the direction of the groove base and the first cavity remains between the groove base and the respective conductor shell. Therefore, firstly the first cavity is provided, in particular for the first inlet channel, and secondly mechanically stable positioning of the respective lower conductor in the respective groove is ensured.

In particular, the respective conductor shell can be designed in two parts by comprising a first conductor shell part, which has an essentially U-shaped cross-section in a plane perpendicular to the axial direction, and a second conductor shell part. The second conductor shell part is designed as a kind of cover for the first conductor shell part, so the respective conductor arranged in the conductor shell is surrounded by the two conductor shell parts, viewed perpendicularly to the axial direction. Particularly good enclosure of the respective conductor is achieved in particular in that the second conductor shell part has two grooves, and the first conductor shell part two corresponding tongues for a respective tongue and groove connection. For sealing and therefore protection of the respective conductor from fluid flowing in the respective cavity, in particular, owing to its advantageous properties described above, a fluororubber can be used in the region of the tongue and groove joint. Furthermore, the respective conductor shell can be pre-tensioned in the circumferential direction with this material, owing to its elasticity, and this further improves fixing of the respective conductor in the respective groove.

In a further advantageous embodiment of the invention, at least a first insert is provided which in each case has an H-shaped cross-section in a plane perpendicular to the axial direction, wherein the respective first insert is arranged between the respective conductor shell of the lower electrical conductor on the one hand and the respective conductor shell of the upper electrical conductor on the other hand and is designed in such a way that a second or third, axially extending cavity, in particular for a first outlet channel or a second inlet channel, remains between the respective conductor shell of the lower conductor or the upper conductor on the one hand and the respective first insert on the other hand.

The respective first insert allows mechanically stable positioning of the respective upper conductor in the respective groove and simultaneously provides the second and third cavity, in particular for the first outlet channel and the second inlet channel. For this purpose, the respective first insert is designed to be H-shaped in a cross-section perpendicular to the axial direction, with the respective first insert serving as a type of spacer between the two adjacent conductors and creating the second and third cavities thereby.

In a further advantageous embodiment of the invention, the respective first insert, in a plane perpendicular to the axial direction, has two outer webs which point in the direction of the groove opening and are arranged at least in certain sections in the circumferential direction between the respective conductor shell of the upper conductor on the one hand and the respective groove wall on the other hand, wherein the two outer webs taper in the direction of the groove opening and the respective conductor shell of the upper conductor tapers in certain sections in the direction of the groove base in such a way that the respective conductor shell of the upper conductor is non-positively fixed in the radial direction.

The respective outer web of the H-shaped first insert pointing in the direction of the respective groove opening is therefore arranged between the respective conductor shell of the upper conductor and the groove wall, with the two outer webs tapering in the direction of the groove opening. Non-positive fixing of the respective conductor shell of the upper conductor in the radial direction is achieved in particular with a constant groove width in the region of the upper conductor in that the respective conductor shell of the upper conductor tapers in certain sections in the direction of the groove base. Therefore, firstly the respective first insert can be introduced into the respective groove, and then the respective conductor shell of the upper conductor can be introduced into the respective groove by pressing this conductor shell between the two outer webs of the respective first insert in the direction of the groove base. This results in reliable positioning of the respective upper conductor as a whole, and at the same time the third cavity is formed, in particular for the second inlet channel.

In a further advantageous embodiment of the invention, at least one second insert is provided, which in each case has a U-shaped cross-section in a plane perpendicular to the axial direction, with the respective second insert being arranged and designed in such a way that a fourth axially extending cavity, in particular for a second outlet channel, remains between the respective conductor shell of the upper conductor on the one hand and the respective second insert on the other hand.

The respective second insert is preferably positioned in such a way that its U-shaped cross-section, viewed perpendicularly to the axial direction, points toward the groove base. In principle, an arrangement of the respective second insert is also conceivable in which its U-shaped cross-section, viewed perpendicularly to the axial direction, points in one of the circumferential directions or towards the groove opening. The fourth cavity, which is provided in particular for the second outlet channel, remains between the respective second insert and the respective conductor shell of the upper conductor. If the U-shaped cross-section points in the direction of the groove opening, the fourth cavity can in particular be closed by a corresponding groove closure.

In a further advantageous embodiment of the invention, the respective second insert, in a plane perpendicular to the axial direction, has two inner webs which point in the direction of the groove base and are arranged at least in certain sections in the circumferential direction between the respective conductor shell of the upper conductor on the one hand and the respective groove wall on the other hand, with the two inner webs tapering in the direction of the groove base and the respective conductor shell of the upper conductor tapering in certain sections in the direction of the groove opening in such a way that the respective conductor shell of the upper conductor and the respective second insert are non-positively fixed in the radial direction.

The respective inner web of the U-shaped second insert pointing in the direction of the groove base is therefore arranged between the respective conductor shell of the upper conductor and the groove wall, with the two inner webs tapering in the direction of the groove base. Non-positive fixing of the respective conductor shell of the upper conductor in the radial direction is achieved or reinforced in particular with a relaxed groove width in the region of the upper conductor in that the respective conductor shell of the upper conductor tapers in certain sections in the direction of the groove opening. Therefore, firstly the respective conductor shell of the upper conductor can be introduced into the respective groove and then the respective second insert can be introduced into the respective groove by the respective inner web of the second insert being introduced into the gap between the conductor shell of the upper conductor and the groove wall, and the second insert part being pressed in the direction of the groove base. This results in reliable positioning of the respective upper conductor and the respective second insert overall, and at the same time the fourth cavity is formed, in particular for the second outlet channel.

In a further advantageous embodiment of the invention, two respective inserts are arranged one behind the other in the axial direction, wherein a respective axial gap remains in the region of the axial center between the two respective inserts, wherein the first cavity and the third cavity in the region of the axial center are closed by a respective cover, wherein the second cavity and the fourth cavity at the respective axial end face are closed by means of a respective cover.

Due to such a configuration of the active part, the fluid is supplied in the active part at its two end faces and led out again from the active part in the region of its axial center. The first and the third cavities serve as an inlet channel or the second and the third cavities as an outlet channel for the lower and upper conductors. To avoid undesirable flow losses, respective covers are provided which close the first and the third cavities in the region of the axial center and the second and the fourth cavities at the respective axial end face.

In a further advantageous embodiment of the invention, the respective conductor shell has recesses running in the radial direction for forming the respective connecting channel.

The respective recess preferably runs largely or completely along the side surface of the respective conductor, with the side surface extending in the radial direction and in the axial direction. Therefore, the recesses provide for a flow of fluid around the respective conductor, so good cooling of the respective conductor can be ensured.

In order to minimize the risk of potential electrical breakdowns in the region of the winding heads at the respective axial end face of the active part, it can be advantageous to not provide any recesses of this kind in the respective conductor shell in the immediate vicinity of the respective axial end face. Depending on the size of the active part, the applied electrical voltage and the insulating properties of the main insulator and the sub-conductor insulator, it can be appropriate to provide none of the recesses discussed above, starting from the respective axial end face of a few centimeters up to a few tens of centimeters. Similarly, it can also be advantageous in the region of the described gap to not provide any recesses of this kind in the respective conductor shell in the immediate vicinity of the gap.

In a further advantageous embodiment of the invention, the respective groove in the radial direction is closed in the region of the groove opening by means of a groove closure element, with a tolerance compensation element being arranged between the respective groove closure element and the at least one conductor.

For the respective tolerance compensation element, in particular a fluororubber can be used, which, as has already been described above, is characterized by its chemical resistance, even under adverse environmental conditions, and good electrical insulating properties. The fluororubber (FPM) can also be present, for example, in the form of a perfluoro rubber (FFPM).

In a further advantageous embodiment of the invention, the respective main insulator and/or the respective sub-conductor insulator comprises polytetrafluoroethylene (PTFE).

The use of polytetrafluoroethylene for the respective main insulator and/or for the respective sub-conductor insulator offers great advantages, even with respect to the use of the polyetheretherketone (PEEK) already described above. For example, PTFE has a continuous use temperature of −200° C. to +260° C. Furthermore, PTFE has nearly complete chemical resistance, since the linear combination of fluorine and carbon to polytetrafluoroethylene produces one of the strongest bonds in inorganic chemistry due to the high electronegativity of fluorine.

Just like PEEK, PTFE is resistant to hydrolysis, wherein the respective creep resistance is similarly also good but with PTFE is adjusted by the addition of suitable fillers. The closely spaced static and dynamic coefficients of friction of PTFE produce excellent sliding properties which prevent the “stick-slip effect”, in other words an abrupt change from sliding and stopping.

A process fluid is preferably used as fluid in the proposed fluid-cooled active part, in the proposed electric machine or in the proposed drive system. As already described above, the process fluid can be in liquid or gaseous form, and in particular be a process liquid, such as, for example crude oil, or a process gas, such as, for example natural gas. For this purpose, in particular the described advantageous materials can be used, in other words, in particular polyetheretherketone (PEEK) or polytetrafluoroethylene (PTFE) for the respective main insulator and/or for the respective sub-conductor and fluororubber (FPM) or perfluoro rubber (FFPM) for various seals and intermediate parts. Due to the use of said materials, the present invention is therefore ideally suited for operation in the environment of acidic or other aggressive process fluids, which for cooling are also guided in the proposed active part.

The invention will be described and illustrated in more detail below with reference to the exemplary embodiments illustrated in the figures, in which:

FIG. 1-12 show first to fifth exemplary embodiments of the proposed fluid-cooled active part, and

FIG. 13 shows an exemplary embodiment of the proposed electric machine and the proposed drive system.

FIG. 1 shows a first exemplary embodiment of the proposed fluid cooled active part 1, with a perspective detail of a cross-section perpendicular to the axial direction 50 through the active part 1 being shown.

The active part 1 is essentially hollow cylindrical, so an axial direction 50, a radial direction 51 and a circumferential direction 52 are defined. The active part 1 has axially extending grooves 2 and 3 electrical conductors, which are each arranged at least in certain sections in the respective groove 2. For the sake of clarity, FIG. 1 only indicates one conductor 3.

The respective conductor 3 is composed of a plurality of sub-conductors 4. Arranged between the respective conductor 3 and the respective groove 2 is a respective main insulator 5, with the respective conductor 4 being surrounded by a sub-conductor insulator 6.

Furthermore, the active part has a respective cooling channel 7 for guiding the fluid, in particular a process fluid, with the respective cooling channel 7 being arranged between the respective main insulator 5 and the sub-conductor insulator 6.

As indicated in FIG. 1, the respective groove 2 has a groove base 11, two groove walls 12, and a groove opening 13, with the grooves 2 being open radially inwards in the framework of the exemplary embodiment. In principle, the grooves 2 can also be open radially outwards.

FIG. 2 shows a second exemplary embodiment of the proposed fluid-cooled active part 1. The same reference numerals as in FIG. 1 designate the same objects.

Since the second exemplary embodiment has some similarities with the first exemplary embodiment, some differences will be explained below. The active part 1 of the second exemplary embodiment is characterized inter alia by the fact that a defined flow direction 43 is specified for the fluid within the respective groove 2. The respective cooling channel 7 comprises an inlet channel 8, an outlet channel 9, and a respective connecting channel 10, which fluidically connects the inlet channel 8 to the outlet channel 9. The inlet channel 8 is arranged between the electrical conductor 3 and the groove base 11 and the outlet channel 9 is arranged between the respective conductor and the groove opening 13. The respective connecting channel 10 is primarily arranged between the conductor 3 and one of the two groove walls 12.

FIG. 3 shows a third exemplary embodiment of the proposed fluid-cooled active part 1, with a detail of a cross-section perpendicular to the axial direction 50 through the active part 1 being shown.

Within the framework of the exemplary embodiment, two electrical conductors 3 a, 3 b are provided in the respective groove 2, and these are arranged one above the other in the radial direction 51. The conductor 3A is the upper conductor facing the groove opening 13 and the conductor 3B is the lower conductor facing the groove base 11. However, it is also possible for just one of the two conductors 3A, 3B to be provided in a variation of the exemplary embodiment.

A respective main insulator 5 is associated with each of the two conductors 3A, 3B, and in each case comprises two essentially C-shaped insulating half-shells 14. The two respective insulating half-shells 14 together surround the respective conductor 3A, 3B in a plane perpendicular to the axial direction 50. The two insulating half-shells 14 are arranged essentially symmetrically to the groove center 15 in the circumferential direction 52 of the respective groove 2. In the radial direction 51, the two respective insulating half-shells 14 are sealed by a respective sealing element 16, with the respective sealing element 16 in particular comprising a fluororubber. Arranged within a pair of insulating half-shells 14 are an inlet channel 8 and an outlet 9.

To simplify the sealing of the two respective insulating half-shells 14 and make it more reliable, the respective insulating half-shell 14 can in each case have a sort of hook 44 in the region of the supporting or contact lines, and this points toward the respective conductor 3A, 3B in the radial direction 51. Said sealing element 16 is, as indicated in FIG. 3, arranged between two hooks 44 of two mating insulating half-shells 14. The hooks 44 should be regarded as optional. Similarly optional is a spacer 45 which is arranged between the plurality of sub-conductors 4 and the respective insulating half-shell 14, which, however, creates space for the respective connecting channel 10 in the framework of the exemplary embodiment.

An intermediate element (not shown) can be provided in the radial direction 51 between the insulating half-shells 14 of the upper conductor 3A and the lower conductor 3B a for sealing and for tolerance compensation.

FIGS. 4 to 8 show a fourth exemplary embodiment of the proposed fluid-cooled active part 1, with FIGS. 6 and 7 illustrating some details and otherwise a perspective detail of a cross-section perpendicular to the axial direction 50 through the active part 1 being shown.

Within the framework of the exemplary embodiment, two electrical conductors 3 a, 3 b are provided in the respective groove 2, and these are arranged one above the other in the radial direction 51. The conductor 3A is the upper conductor facing the groove opening 13 and the conductor 3B is the lower conductor facing the groove base 11. However, it is also possible for just one of the two conductors 3A, 3B to be provided in a variation of the exemplary embodiment.

The respective main insulator 5 is designed in such a way that it largely covers the groove base 11 and the two groove walls 12 of the respective groove 2.

As is clear in particular from FIGS. 5 and 8, a plurality of channel half-shells 17 is arranged one behind the other in the axial direction 50, with some of the channel half-shells being arranged mirror-inverted to other channel half-shells 17 with respect to the groove center 15 in the circumferential direction 52 of the respective groove 2. In a plane perpendicular to the axial direction 50, the respective channel half-shell 17 has an essentially U-shaped cross-section and largely surrounds the respective conductor 3A, 3B.

Viewed in a plane perpendicular to the axial direction 50, the respective channel half-shell 17 has a radial web 18 as well as two pairs of circumferential webs 19. The respective radial web 18 extends in the radial direction along the respective conductor 3 and the respective circumferential web 19 points in the circumferential direction 52, with the circumferential webs 19 being connected by means of the radial web 18.

The respective inlet channel 8 and the respective outlet channel 9 are designed as follows by means of circumferential webs 19. The inlet channel 8 is arranged in the region of that pair of circumferential webs 19 which is closer to the groove base 11, (in other words, at the bottom in FIGS. 4 to 8), and the outlet channel 9 is arranged in the region of that pair of circumferential webs 19 which is closer to the groove opening 13 (in other words, at the top in FIGS. 4 to 8).

The active part 1 has first channel half-shells 17A, which, as shown in FIG. 7, have middle circumferential webs 19 which have a respective through-opening 20 (upper one of the middle circumferential webs 19 in FIG. 7) or form a respective through-opening 20 which remains between the respective middle circumferential ridge 19 and the respective main insulator 5 (lower one of the central circumferential webs 19 in FIG. 7). The last-mentioned embodiment is achieved in that the corresponding circumferential web is designed somewhat shorter in the circumferential direction 19 than the remaining circumferential webs 19 and therefore the through-opening 20 is formed. By way of such an embodiment of the respective first channel half-shell 17A, at least some of the respective connecting channel 10 is formed by means of at least one of the two central circumferential webs 19. In a variation of the exemplary embodiment, the respective first channel half-shell 17A can have just one through-opening 20 or two identical ones of the above through-openings 20.

Furthermore, the active part 1 has second channel half-shells 17B in which in each case the circumferential webs 19 of a pair or both pairs of circumferential webs 19 are connected by means of a respective end web 21, as shown in FIG. 6. The second channel half-shells 17B are designed in such a way that, viewed in a plane perpendicular to the axial direction 50, they each have a rectangular cross-section for guiding the respective cooling channel 7. In the present exemplary embodiment, two such rectangular cross-sections are formed, one for the inlet channel 8 and one for the outlet channel 9.

Provided in the radial direction 51 between the channel half-shells 17 of the upper conductor 3A and the lower conductor 3B is an intermediate element 22 for sealing and for tolerance compensation.

As indicated in FIG. 8 by the arrows 43 for the flow direction of the fluid, the fluid is introduced into the respective inlet channel 8 and it is guided firstly in the axial direction 50 by means of the second channel half-shells 17B. Subsequently, the fluid is guided by means of the first channel half-shells 17A through corresponding through-openings 20 in the radial direction 51 into the respective connecting channel 10, to be then led into the respective outlet channel 9 and finally to be led out in the axial direction 15 from the arrangement of the channel half-shells 17.

FIGS. 9 to 12 show a fifth exemplary embodiment of the proposed fluid-cooled active part 1, with a detail or a perspective detail of a cross-section perpendicular to the axial direction 50 through the active part 1 being shown and FIG. 10 showing details of a conductor shell 23 for an upper electrical conductor 3A.

Within the framework of the exemplary embodiment, two electrical conductors 3A, 3B are provided in the respective groove 2, and these are arranged one above the other in the radial direction 51. The conductor 3A is the upper conductor facing the groove opening 13 and the conductor 3B is the lower conductor facing the groove base 11. However, it is also possible for just one of the two conductors 3A, 3B to be provided in a variation of the exemplary embodiment.

The respective main insulator 5 is designed in such a way that it largely covers the groove base 11 and the two groove walls 12 of the respective groove 2.

In the present exemplary embodiment, a respective conductor shell 23 is provided which surrounds the respective conductor 3A, 3B in a plane perpendicular to the axial direction 50. The respective groove 2 has a groove region 47 along which the groove width 28 decreases in the radial direction 51 toward the groove base 11 so the respective groove 2 tapers there in the direction of the groove base 11. The respective conductor shell 23 of the lower conductor 3B likewise tapers in the corresponding region in the direction of the groove base 11, with the respective tapered portions being designed in such a way that the respective conductor shell 23 of the lower conductor 3B is positively fixed in the direction of the groove base 11, and a first, axially extending cavity 24 remains for the first inlet channel 8A between the groove base 11 and the respective conductor shell 23 of the lower conductor 3B. In particular, the groove width 28 can remain constant in the region of the first cavity 24.

Furthermore, a respective first insert 25 is provided which has an H-shaped cross-section in a plane perpendicular to the axial direction 50. The respective first insert 25 is arranged between the respective conductor shell 23 of the lower conductor 3B and the respective conductor shell 23 of the upper electrical conductor 3A. The respective first insert 25 is designed in such a way that a second axially extending cavity 26 for a first outlet 9A remains between the respective conductor shell 23 of the lower conductor 3B on the one hand and the respective first insert 25 on the other hand. Furthermore, a third, axially extending cavity 27 for a second inlet channel 8B remains between the respective conductor shell 23 of the upper conductor 3A on the one hand and the respective first insert 25 on the other hand.

In a plane perpendicular to the axial direction 50, the respective first insert 25 has two outer webs 29, which point in the direction of the groove opening 13 and are arranged in certain sections in the circumferential direction 52 between the respective conductor shell 23 of the upper conductor 3A on one hand and the respective groove wall 12 on the other hand. The two outer webs 29 of the respective first insert 25 taper in the direction of the groove opening 13 and the respective conductor shell 23 of the upper conductor 3A tapers in certain sections in the direction of the groove base 11, with the tapered sections being designed in such a way that the respective conductor shell 23 of the upper conductor 3A is non-positively fixed in the radial direction 51.

Furthermore, a respective second insert 30 is provided which has a U-shaped cross-section in a plane perpendicular to the axial direction 50. The respective second insert 30 is arranged and designed in such a way that a fourth axially extending cavity 31 for a second outlet channel 9B remains between the respective conductor shell 23 of the upper conductor 3A on the one hand and the respective second insert 30 on the other hand.

In a plane perpendicular to the axial direction 50, the respective second insert 30 has two inner webs 32 which point in the direction of the groove base 11 and in certain sections in the circumferential direction are arranged between the respective conductor shell 23 of the upper conductor 3A on the one hand and the respective groove wall 12 on the other hand. The two inner webs 32 of the respective second insert 30 taper in the direction of the groove base 11, with the respective conductor shell 23 of the upper conductor 3A tapering in certain sections in the direction of the groove opening 13. The tapered sections are designed in such a way that the respective conductor shell 23 of the upper conductor 3A and the respective second insert are non-positively fixed in the radial direction 51 30.

Within the framework of the exemplary embodiment, the respective conductor shell 23 is designed in two parts by comprising a first conductor shell part 23A, having an essentially U-shaped cross-section in a plane perpendicular to the axial direction 50, and a second conductor shell part 23B, as shown in FIGS. 9 and 10. The second conductor shell part 23B is in this case designed as a kind of cover for the first conductor shell part 23A. In order to surround the respective conductor 3A, 3B, particularly well, the second conductor shell part 23B has two grooves and the first conductor shell part 23A two corresponding tongues for a respective tongue and groove joint. For sealing and therefore protection of the respective conductor 3A, 3B from the fluid flowing into the respective cavity, in particular, owing to its advantageous properties described above, a fluororubber can be used in the region of the tongue and groove joint.

As is clear in particular from FIGS. 11 and 12, within the framework of the exemplary embodiment, two respective inserts 15, 30 are arranged one behind the other in the axial direction 50, with a respective axial gap 33 remaining in the region of the axial center between the two respective inserts 25, 30. The first cavity 24 and the third cavity 27 are closed in the region of the axial center by means of a respective cover 34. Further covers 34 are provided for closing the second cavity 26 and the fourth cavity 31 at the respective axial end face.

As illustrated in FIG. 10, the respective conductor shell 23 has recesses 35, which run in the radial direction 51 and form the respective connecting channel 10.

In order to minimize the risk of potential electrical breakdowns in the region of the winding heads at the respective axial end face of the active part 1, no such recesses 35 are provided in the respective conductor shell 23 in the immediate vicinity of the respective axial end. Analogously, no such recesses 35 are provided in the respective conductor shell 23 in the immediate vicinity of the illustrated gap 33 either.

FIG. 13 shows an exemplary embodiment of the proposed electric machine 38 and the proposed drive system 41, with a cross-section along the axial direction 50 being shown.

The electric machine 38 has a stator 39 and a rotatably mounted rotor 40, with the stator 39 and/or the rotor 40 being designed as the proposed, fluid-cooled active part. The electric machine 38 can be operated with an electrical voltage in the range of a few kilovolts, in particular a few tens of kilovolts.

The electric machine 38 is part of the drive system 41, further comprising a fluid energy machine 42 for the fluid, with the fluid energy machine 42 being designed as a compressor, in particular for a process gas, or as a pump, in particular for a process fluid. The arrows 43 indicate the flows of the fluid in the electric machine 38 and in the fluid energy machine 42.

To summarize, the invention relates to a fluid cooled active part for an electric machine, wherein the active part is essentially cylindrical or hollow-cylindrical, having axially extending grooves, at least one electrical conductor, which in each case is arranged at least in certain sections in the respective groove and which is composed of a plurality of sub-conductors, a respective main insulator, which is arranged between the respective conductor and the respective groove, and a respective sub-conductor insulator which surrounds the respective sub-conductor. Furthermore, the invention relates to an electric machine having a fluid-cooled active part of this kind designed as a stator, and/or a fluid-cooled active part of this kind designed as a rotatably mounted rotor, wherein the electric machine can be operated with an electrical voltage in the range of at least a few kilovolts, preferably a few tens of kilovolts. Finally, the invention relates to a drive system having an electric machine of this kind, and a fluid energy machine for the fluid, wherein the fluid energy engine is designed, for example, as a compressor or, in particular for a process gas, or as a pump, in particular for a process fluid.

In order to overcome drawbacks from the prior art and to provide a fluid-cooled active part which is powerful, compact and in particular resistant in the environment of the fluid and a process fluid, it is proposed that the active part has a respective cooling channel for guiding the fluid, in particular a process fluid, wherein the respective cooling channel is arranged between the respective main insulator and the respective sub-conductor insulator. Furthermore, a corresponding electric machine and a corresponding drive system are proposed. 

1. A fluid-cooled active part (1) for an electric machine (38), wherein the active part (1) is essentially cylindrical or hollow cylindrical, having axially extending grooves (2), at least one electrical conductor (3), which in each case is arranged in the respective groove (2) at least in certain sections and which is composed of a plurality of sub-conductors (4), a respective main insulator (5) which is arranged between the respective conductor (3) and the respective groove (2), and a respective sub-conductor insulator (6) which surrounds the respective sub-conductor (4), characterized by a respective cooling channel (7) for guiding the fluid, in particular a process fluid, wherein the respective cooling channel (7) is arranged between the respective main insulator (5) and the respective sub-conductor insulator (6).
 2. The fluid-cooled active part (1) as claimed in claim 1, wherein the respective cooling channel (7) has an inlet channel (8), an outlet channel (9) and a respective connecting channel (10) for fluidically connecting the inlet channel (8) to the outlet channel (9), wherein the respective groove (2) has a groove base (11) and two groove walls (12), wherein the respective inlet channel (8) or outlet channel (9) is arranged between the respective conductor (3) on the one hand and the groove base (11) or the groove opening (13) that opposes the groove base (11) in the radial direction (51) on the other hand, wherein the respective connecting channel (10) is arranged at least predominantly between the respective conductor (3) on the one hand and one of the two groove walls (12) on the other hand.
 3. The fluid-cooled active part (1) as claimed in one of the preceding claims, wherein the respective main insulator (5) has two essentially C-shaped insulating half-shells (14) which together essentially surround the respective conductor (3) in a plane perpendicular to the axial direction (50), wherein the two respective insulating half-shells (14) are arranged essentially symmetrically to the center of the groove (15) in the circumferential direction (52) of the respective groove (2), wherein the two respective insulating half-shells (14) are sealed in the radial direction (51) by means of a respective sealing element (16), comprising in particular a fluororubber.
 4. The fluid-cooled active part (1) as claimed in claim 1 or 2, wherein the respective main insulator (5) at least largely covers the groove base (11) and the two groove walls (12) of the respective groove (2), wherein a plurality of channel half-shells (17) is arranged one behind the other in the axial direction (50), wherein the respective channel half-shell (17) has an essentially U-shaped cross-section in a plane perpendicular to the axial direction (50) and largely surrounds the respective conductor (3) in this plane.
 5. The fluid-cooled active part (1) as claimed in claims 2 and 4, wherein the respective channel half-shell (17), viewed in a plane perpendicular to the axial direction (50), has at least one radial web (18) extending in each case in the radial direction (51) along the respective conductor (3), as well as two pairs of circumferential webs (19) pointing in the circumferential direction (52), which are connected by means of the radial web (18), wherein the one pair of circumferential webs (19) is designed for forming the respective inlet channel (8) and the other pair of circumferential webs (19) for forming the respective outlet channel (9), wherein in at least a first channel half-shell (17A) in each case at least one of the two central circumferential webs (19) is designed for forming at least some of the respective connecting channel (10).
 6. The fluid-cooled active part (1) as claimed in claim 5, wherein between at least one of the two central circumferential webs (19) of the respective first channel half-shell (17A) on the one hand and the respective main insulator (5) on the other hand, a respective through-opening (20) remains and/or at least one of the two central circumferential webs (19) of the respective first channel half-shell (17A) has a respective through-opening (20).
 7. The fluid-cooled active part (1) as claimed in claim 5 or 6, wherein in at least one second channel half-shell (17B), in each case the circumferential webs (19) of at least one of the two pairs of circumferential webs (19) are connected in such a way by means of a respective end web (21) that the respective second channel half-shell (17B), viewed in a plane perpendicular (50) to the axial direction, has a rectangular cross-section for guiding the respective cooling channel (7).
 8. The fluid-cooled active part (1) as claimed in one of claims 3 to 7, wherein at least two electrical conductors (3A, 3B) are arranged in the respective groove (2) one above the other in the radial direction (51), wherein a respective intermediate element (22) is provided for sealing and/or for tolerance compensation, and this is arranged in the radial direction (51) between one of the half-shells (14, 17) of the upper electrical conductor (3A) on the one hand and one of the half-shells (14, 17) of the lower electrical conductor (3b) on the other hand.
 9. The fluid-cooled active part (1) as claimed in claim 1 or 2, wherein the respective main insulator (5) at least largely covers the groove base (11) and the two groove walls (12) of the respective groove (2), wherein at least two electrical conductors (3) are arranged in the respective groove (2) one above the other in the radial direction (51), wherein a respective conductor shell (23) is provided which surrounds the respective conductor (3) in a plane perpendicular to the axial direction (50), wherein both the respective groove (2), at least in the region of the lower electrical conductor (3B), as well as the respective conductor shell (23) of the lower electrical conductor (3B) taper in the direction of the groove base (11) in such a way that the respective conductor shell (23) of the lower conductor (3B) is positively fixed in the direction of the groove base (11), and a first, axially extending cavity (24), in particular for a first inlet channel (8A), remains between the groove base (11) and the respective conductor shell (23) of the lower electrical conductor (3B).
 10. The fluid-cooled active part (1) as claimed in claim 9, wherein at least a first insert (25) is provided which in each case has an H-shaped cross-section in a plane perpendicular to the axial direction (50), wherein the respective first insert (25) is arranged between the respective conductor shell (23) of the lower conductor (3B) on the one hand, and the respective conductor shell (23) of the upper electrical conductor (3A) on the other hand, and is designed in such a way that a second or third, axially extending cavity (26 or 27), in particular for a first outlet channel (9A) and a second inlet channel (8B), remains between the respective conductor shell (23) of the lower conductor (3B) or the upper conductor (3A) on the one hand and the respective first insert (25) on the other hand.
 11. The fluid-cooled active part (1) as claimed in claim 10, wherein the respective first insert (25), in a plane perpendicular to the axial direction (50), has two outer webs (29) which point in the direction of the groove opening (13) and are arranged at least in certain sections in the circumferential direction (52) between the respective conductor shell (23) of the upper conductor (3A) on the one hand and the respective groove wall (12) on the other hand, wherein the two outer webs (29) taper in the direction of the groove opening (13) and the respective conductor shell (23) of the upper conductor (3A) tapers in certain sections in the direction of the groove base (11) in such a way that the respective conductor shell (23) of the upper conductor (3A) is non-positively fixed in the radial direction (51).
 12. The fluid-cooled active part (1) as claimed in claim 10 or 11, wherein at least a second insert (30) is provided, which in each case has a U-shaped cross-section in a plane perpendicular to the axial direction (50), wherein the respective second insert (30) is arranged and designed in such a way that a fourth, axially extending cavity (31), in particular for a second outlet channel (9B), remains between the respective conductor shell (23) of the upper conductor (3A) on the one hand and the respective second insert (30) on the other hand.
 13. The fluid-cooled active part (1) as claimed in claim 12, wherein the respective second insert (30) in a plane perpendicular to the axial direction (50) has two inner webs (32) which point in the direction of the groove base (11) and are arranged at least in certain sections in the circumferential direction (52) between the respective conductor shell (23) of the upper conductor (3A) on the one hand and the respective groove wall (12) on the other hand, wherein the two inner webs (32) taper in the direction of the groove base (11) and the respective conductor shell (23) of the upper conductor (3A) tapers in certain sections in the direction of the groove opening (13) in such a way that the respective conductor shell (23) of the upper conductor (3A) and the respective second insert (30) are positively fixed in the radial direction (51).
 14. The fluid-cooled active part (1) as claimed in claim 12 or 13, wherein two respective inserts (25, 30) are arranged one behind the other in the axial direction (50) and a respective axial gap (33) remains in the region of the axial center between the two respective inserts (25, 30), wherein the first cavity (24) and the third cavity (27) in the region of the axial center are closed by means of a respective cover (34), wherein the second cavity (26) and the fourth cavity (31) are closed at the respective axial end face by a respective cover (34).
 15. The fluid-cooled active part (1) as claimed in one of claims 9 to 14, wherein the respective conductor shell (23) has recesses (35) extending in the radial direction (51) for forming the respective connecting channel (10).
 16. The fluid-cooled active part (1) as claimed in one of the preceding claims, wherein the respective groove (2) is closed in the radial direction (51) in the region of the groove opening (13) by means of a groove closure element (36), wherein a tolerance compensating element is arranged between the respective groove closure element (36) and the at least one conductor (3).
 17. The fluid-cooled active part (1) as claimed in one of the preceding claims, wherein the respective main insulator (5) and/or the respective sub-conductor insulator (6) comprises polytetrafluoroethylene (PTFE).
 18. An electric machine (38) having a fluid-cooled active part (1) designed as a stator (39) as claimed in one of the preceding claims and/or a fluid-cooled active part (1) designed as a rotatably mounted rotor (40) as claimed in one of the preceding claims, wherein the electric machine (38) can be operated with an electrical voltage in the range of at least a few kilovolts, preferably a few tens of kilovolts.
 19. A drive system (41) having an electric machine (38) as claimed in claim 18 and a fluid energy machine (42) for the fluid, wherein the fluid energy machine (42) is designed for example as a compressor, in particular for a process gas, or as a pump, in particular for a process liquid. 